Does exercise reduce breast-cancer risk?

Women needed for hutch activity study

Why do women who exercise regularly have a 30-percent reduced risk of breast cancer? Is it the exercise, or is it because they eat healthier foods and live generally healthier lives?

"Our understanding of the relationship between exercise and cancer is about where research into exercise and cardiovascular health was 20 years ago," says Anne McTiernan, M.D., Ph.D., a cancer prevention researcher in the Fred Hutchinson Cancer Research Center's Public Health Sciences Division. "We've observed an association between exercise and cancer risk, even defined risk factors. Now we want to look at the mechanisms to explain these research results."

McTiernan leads the Physical Activity for Total Health project, a National Cancer Institute-funded initiative that is examining the effect of exercise on the body's hormones and immune system.

The project will enroll 170 sedentary, post-menopausal women in an exercise program. Half of the women will focus on aerobic and strength conditioning, and the other half on stretching exercises. To date, about 60 women have volunteered to participate; recruitment will continue through the end of next year.

It is the first project of its kind to look at exercise and breast-cancer risk in women over age 55, McTiernan says.

"By participating in this study, women will not only play an important role in advancing our understanding of breast-cancer development but will also learn how to make exercise or stretching an enjoyable part of their life," she says.

To qualify for the study, a woman must be 50 to 75 years old, in good health and a nonsmoker, past menopause, not using menopausal hormones and planning to remain in western Washington during the next year. Those who would like to participate can call the Physical Activity for Total Health study information line at (206) 667-7177.

Women who take part in this year-long study will be randomly assigned to one of two exercise groups. One group will be taught aerobic and weight-training exercises under the supervision of a trainer for the first three months, then will be expected to continue with a variety of group and individual fitness activities during the remaining nine months.

The other group will focus on a program of stretching exercises, and participants will receive instruction on various health-related topics. Classes will be held at the Hutchinson Center or at an off-campus UW exercise physiology facility in north Seattle. All classes and training will be free of charge.

Researchers will monitor the women's hormones, particularly estrogen, because high estrogen levels can increase breast-cancer risk. McTiernan also will collaborate with the immunology lab of University of Washington rheumatologist Mark H. Wener, M.D., associate professor of laboratory medicine, to measure the women's immune function at several points throughout the year.

The researchers will be examining factors involved in immune function, such as the number and type of circulating immune cells, natural killer-cell activity, and the ability of lymphocytes (white blood cells) to grow and divide. Also monitored will be the number and severity of upper-respiratory infections (i.e., colds) the women experience during the study.

"By participating in projects like this, local women can make a wonderful contribution to cancer prevention research," McTiernan says.

# # #

NOTE: To schedule an interview with Dr. McTiernan or a study participant in an exercise class, please call Kristen Woodward at (206) 667-5095.